December 3, 2023

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Intestinal immunity is much important for whole immune system

Intestinal immunity is much important for whole immune system

Intestinal immunity is much important for whole immune system.  The human body’s largest immune cell population exists in the intestinal mucosa, which is closely related to many diseases.

Intestinal immunity is much important for whole immune system

The human body’s largest immune cell population exists in the intestinal mucosa, which is closely related to many diseases. The intestine is obviously the digestive organ, so why is it an immune organ? The natural mission of the intestine is digestion and absorption, and its design first considers how to perform digestion and absorption efficiently. There are countless villi inside the small intestine, and there are countless microvilli on each villus. The total surface area reaches 300 square meters, which is much larger than the surface area of ​​the skin (2 square meters) and the lung mucosal system (80 square meters).

The surface of the intestine is covered with a mucosa composed of a single layer of epithelial cells, and underneath the mucosa is a densely packed microvessel and chyle system. Food from the mouth, stomach to the small intestine is digested and decomposed into small molecules such as amino acids, glucose, and fatty acids under precise control, which are absorbed through the mucous membranes, and then quickly enter the circulatory system from capillaries and chylotubes. This is the design of the intestinal tract for effective digestion and absorption. It has a surprisingly large area, efficient mucosal absorption, and efficient material transportation.

Now the problem has emerged. Don’t forget that the intestine is also the most dangerous and dirty place. Numerous germs and poisons that invade the oral cavity, as well as the army of bad bacteria that exist in the intestine, are eagerly waiting for the opportunity to invade the human body. Good and beneficial nutrients can be efficiently absorbed and transported to the whole body; similarly, bad and harmful toxins and germs can also be absorbed and transported efficiently.

Dear friends, when our body designs its defense system, most of the immune army is deployed in the intestine to protect the safety of the intestinal mucosa.

More than 70% of immune cells (such as macrophages, T cells, NK cells, B cells, etc.) are concentrated in the intestine; more than 70% of immunoglobulin A is produced by the intestine and is used to protect the intestine . Therefore, the name of the intestine is actually the most important immune organ.

If the intestines are not good, the enemy forces (bad bacteria) will invade aggressively, the Confederate Army (good bacteria) will retreat steadily, the war will spread to the intestinal mucosa, your immune cells will follow one another, and corpses will be everywhere. Think about it, how can your immune system be good? Therefore, the name of the intestine is actually the front line of immunity.

The human body’s first line of defense is the skin and mucous membranes. The skin covers the body, except for gas, moisture, and a few small molecules like essential oils, unless there is a wound, germs and poisons are not easy to invade. But like the intestines, alveoli, glomeruli, etc., the places in the body that require high-efficiency exchange of substances must be covered by the mucosal system.

The second line of defense is called innate immunity. This system can immediately respond to external infections without education and training. It can only distinguish between the enemy and the enemy, but it cannot selectively respond to specific enemies. Neutrophils, macrophages, and NK cells are the three general members of the innate immune system.



The life cycle of neutrophils is only a short 12h, and they react very quickly. They can reach the infected site 30 to 60 minutes after the invasion of the bacteria, which is regarded as the pioneer of innate immunity.


Macrophages (Macrophages, abbreviated as Mø)

Macrophage (macrophage) is the second wave of attackers, with a long life cycle and can continue to proliferate. They are huge, can swallow germs, and they will issue warnings to inform the acquired immune system of the third line of defense, and begin to make weapons (antibodies or T cells) that can specifically deal with invaders. Therefore, macrophages are not only the main attack force of innate immunity, but also the communication officer that stimulates acquired immunity.


Natural killer cells (Natural killer, NK cells)

Natural killer cells (NK cells) and macrophages have different ways of phagocytosing pathogenic bacteria. They pierce the cells so that the contents of the cells flow out and die. They will not only perform the work of killing pathogens, but also actively seek to attack cells infected by pathogens, as well as cells that have mutated and become cancerous. Our body naturally produces thousands of mutant cells every day. Without strong and diligent natural killer cells, we have long been overwhelmed by cancer cells.


Innate immunity is local and can cause local inflammation, showing symptoms such as redness, swelling, swelling, and pain; while the third line of defense called acquired immunity is comprehensive, specific and memorable The characteristics of fever will also appear clinically.

Basically, it takes about 7 to 10 days from the invasion of viruses and neutrophils and macrophages to the activation of acquired immunity. Therefore, even if people with normal immunity have a cold, even if they don’t take medicine, it takes 7 to 10 days. Will heal naturally.

Acquired immunity can be divided into humoral immunity and cellular immunity. The protagonist of humoral immunity is the various antibodies (also called immunoglobulin, abbreviated as Ig) produced by B cells. The main antibodies are: IgG, the main antibody in the blood; IgA, the antibody secreted into saliva, milk, intestine, respiratory tract and genitourinary tract; IgE, which is related to allergic reactions.

Cellular immunity is an immune response dominated by T cells. T cells are divided into several categories according to their functions. For example, Killer T cells are brave fighters. They attack and kill virus-infected cells. Helper T cells can stimulate B cells. Produce antibodies and various cytokines (Cytokine). We often say to keep Th1 and Th2 in balance, Th refers to helper T cells.


Helper T cells (Th, CD4+T cells)

Killer T cells (CTL, CD8+T cells)


Innate immune neutrophils, macrophages, and natural killer cells, like mobile reconnaissance and defense forces, spread all over the body, always preparing for battle; acquired immune B cells are missile forces and the combat command center, and antibodies are missiles that kill the enemy. The cytokine is a messenger tool for coordinating operations; and the T cell can be compared to a chariot troop on the front line.


B lymphocytes (B cells)

The human body’s immune system is like a net of heaven and earth, destroying foreign pathogens and poisons, and hunting lurking cancer cells in the body. Unless we abuse ourselves and cause immune confusion and internal friction, it will rarely fail. This defense system is truly ingenious and worthy of our gratitude and admiration. What we should do is to treat ourselves well, so that the immune system has no worries and is fully equipped to fight.





(source:internet, reference only)

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